dymd3z

Hello, Maybe someone can help me out in here.
1994 Mustang GT Vert
My problem is, after roughly 3-4 days my mustang battery will be completely dead. Just a few clicks and very dim lights (3days) What I have done so far is, After running the car roughly 15 mins, I shut it down closed all doors and then hooked up a digital multi-meter probe to the neg battery terminal wire and the other probe to the negative battery post on the battery, I got a reading of 12.76 (amps I believe) so I then started snatching fuses and when I got to the power seat/cig lighter/aux power fuse (under hood fuse box) the reading dropped to like 1.6 so I am thinking this is where my voltage is being pulled from and what is draining my battery.
Now my question is what do I do from here?
And did I do the testing correctly?
Can anyone tell me something else I can try to do to narrow this problem down. I have been dealing with this for a few years now every since I got the car and I am sick of dealing with a dead battery when I do get time to take it for a ride.
Only after market part that I have noticed is a radio and i have pulled the radio fuse and left it out for a few days and it done the same thing.

Any advice will be gratefully appreciated. Thanks Again

mattdel

Long as the meter was on amps, that's right.

That fuse only protects the circuits you mentioned, it has no other circuits that aren't labeled. Given the amount of amperage being requested, you can almost guarantee that you have a stuck power seat switch. Unplug them both and test again.

dawson1112

cigarette lighters are notorious for getting things dropped into them , like coins or small screws. Id start there , if you don't use the lighter for anything you can pull the wires off the back of it and disconnect it then see if your still drawing voltage

ttocs

if the stock amps are still in the car(under the rear deck and below the stock radio location) try disconnecting them. Seen alot of them staying on and slowyly draining batteries over the past few years.

LCBlackDep183

ttocs, really? I've been battling a stray drain for a few years now. Never thought about the stock audio.

GT Katie

Since you hooked up a meter between the bat neg & the cable, what you were reading is 12.76 VOLTS, not amps, & if you did have a 12 amp draw your battery would be going dead sooner than 4 days. Best shot is to use a test light (same hook up as before) between the Bat negative post & the cable (the test light will light up) then go back & pull your fuses one at a time "as you watch the light". If you get through all the fuses & the light's still on, start puling the relays & the circuit breakers.

mjr46

best bet is USE A DVOM for the most accurate reading, set to the amp mode, that way you will know for sure when and how much a draw is on the system, 25 to 50 milliamp is the goal at rest., pull fuses until you get under that to isolate the problem circuit

petrock

To test for amps, you need to disconnect the negative battery cable too. You may have done it, but didn’t mention it.


Put the fuse back in and disconnect the cigarette lighter and see if the amp draw goes down to normal. If not, then the drain is something else on that circuit. Possibly a shorted wire.


That depends on if you had the meter set to test amps, not volts and if you had the negative battery cable disconnected when you were testing for amps.


Here is a really good step by step instructions on how to track down a parasitic battery drain:
http://www.wikihow.com/Find-a-Parasitic-Battery-Drain


That is incorrect. One meter lead on the negative battery post and the other on the battery cable (with the cable still attached to the battery) would produce a voltage reading of close to zero volts. He would get 12.x volts if one meter lead was on the power side of the circuit (e.g. positive battery post/cable) or if there was a massive amount of resistance between the two points that the meter leads were touching (e.g. corroded battery cable & terminals). Thats voltage drop testing 101. If the negative battery cable was disconnected if/when he tested for volts he would either get zero volts or ghost voltage depending on the sensitivity of his meter.


A test light will only get you so far. It all depends on how many amps your test light will draw and if it is an incandescent or LED test light. The general rule of thumb is an abnormal battery drain is anything higher then 25-50 milli-amps (0.025 to 0.05 amps). If your test light requires more amps then that it won’t light up. The best way to find a battery drain is with an amp/multi meter.

GT Katie

PetRock--> That is incorrect. One meter lead on the negative battery post and the other on the battery cable (with the cable still attached to the battery) would produce a voltage reading of close to zero volts.
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Katie--> I agree with that part (providing he had left the neg cable attached, but I thought he disconnected it.) IF he didn't disconnect the neg cable & check between cable & the neg post then my mistake for assuming that he did.
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PetRock--> He would get 12.x volts if one meter lead was on the power side of the circuit (e.g. positive battery post/cable) or if there was a massive amount of resistance between the two points that the meter leads were touching (e.g. corroded battery cable & terminals). Thats voltage drop testing 101. If the negative battery cable was disconnected if/when he tested for volts he would either get zero volts or ghost voltage depending on the sensitivity of his meter.
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Katie--> I disagree with that part. He would not get zero volts. IF he disconnected the neg cable from the battery & checked between negative batt post & negative cable he would see battery voltage. I think this is what he did because of the reading he got. It was right in the range of normal battery voltage & I think he was on the volt scale on the meter. Also if that was a 12.7 "amp" draw the battery would be going dead a lot faster than 3-4 days. I've never seen a draw that high.
edit* Correction. I have seen a draw "higher" than 12.7 amps when the starter solonoid was stuck & the wire was smoking lol. Didn't have time to measure it but I'm guessing it was around 40-50 amps as fast as the smoke was coming out ;-)
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PetRock--> A test light will only get you so far. It all depends on how many amps your test light will draw and if it is an incandescent or LED test light. The general rule of thumb is an abnormal battery drain is anything higher then 25-50 milli-amps (0.025 to 0.05 amps). If your test light requires more amps then that it won’t light up. The best way to find a battery drain is with an amp/multi meter.
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Katie--> I agree, the test light isn't the best, but is a lot simpler for someone who doesn't have a lot of experience chasing electrical gremlins. I assumed the O.P. doesn't have a lot of experience with V.O.A. meter or automotive electrical systems because he didn't know if he was reading amps or volts, & it's easier to watch the light while he's pulling fuses than to have to re-read the meter everytime. Another benefit for the test light for a newby is that it won't show ghost voltage. It will only light as long as there's a draw.

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mattdel

The pissing contest is cute, but you're all forgetting that the reading dropped when he took the power seat fuse out. That means explicitly that he wasn't reading voltage, as voltage wouldn't drop at all from pulling a fuse, only amperage draw would.